Process and apparatus for the production of diphenyl



Jan. 17, 1933.

T.. J. SCOT-T V PROCESS AND APPARATUS FOR THE PRODUCTION OF DTPHENYL 2 Shgets-Sheet Filed June 2, 1928' Q Inventor Thomas JScozt By I W Attorneys Jan. 17, 1933. T..J. SCOTT 1,894,283

PROCESS AND APPARATUS FOR THE PRODUCTiON OF DTPHENYL FiledJune 2, 1928 2 Sheets-Sheet 2 m QR Invenl or 4 i Thomas $300 if Patented Jam 17, 1933 UNITED STATES PATENT OFFICE THOMAS J. SCOT'L'OF FOLEY, ALABAMA, ASSIGNOR '10 SWANN RESEARCH, INC A CORPORATION OF ALABAMA PROCESS AND APPARATUS FOR THE PRODUCTION OE DIPHEN'YL Application filed June 2, 1928. Serial Ilo. 282,403.

This invention relates to a method and apparatus for making diphenyl by raising the temperature of benzene, or the commercially known product benzol, to the temperature at which diphenyl is formed.

One of the objects of\this invention is to produce diphenyl on a commercial scale, by a method in which it is easier to control the temperature, rate of flow of gas, and obtain quick cooling of the vapor, than by any method heretofore proposed; and further, to produce diphenylmore economically than is possible by any existing methods.

A further object of the invention is to provide an apparatus in which this method of production may be carried'out.

A still further object is to provide a meth- 0d of supplying the heat necessary for the reaction whereby the tendency for the formation of carbon is lessened, and to provide a means whereby such carbon as may be formed may be removed from the reaction system without interruption of the continuity of the process.

So far as I am aware, the production of diphenyl on a commercial scale is carried out, only by passing benzene vapor over a surface which is heated by electrical means. I have discovered a means of heating benzene vapor by means of fuel heat, such as gas, oil, or solid fuel, for-instance, and in an apparatus which is easier to' control, whereby the factors relating to the reaction are under the necessary control, thereby producing diphenyl by an improved method, and at a lower cost.

The factors which I have found to be of greatest importance, influencing the success-. ful production of diphenyl, are:

1. Means of controlling the temperature in the reacting zone in such a manner that the reacting temperature is maintained, but eYcessive temperature is avoided. 4 i 45 h 2. Supplying all the heat possible for preheating the gas, at a temperature at which little or no diphenyl will be formed.

"3. After the preheating, to subject the benzene vapor for a very short time at a tem- 50 per'ature for the optimum formation of diphenyl, with the minimum side reactions occurring.

4. Providing a means of definite control of the reacting temperature, whereby sufiicient heating (i. e. temperature rise) will be obtained, but overheating will be prevented.

5. Quickly cooling the vapor after its con tact at the reacting temperature, to prevent reversal of the diphenyl equilibrium and the reformation of benzene. 6

I am able to accomplish all the foregoing in the method I propose] and the apparatus which I employ.

-In order that my method may be more clearly understood and be practiced by those who are skilled in the art, I will nowdescribe my method, as follows:

Ben zol which may be in either a liquid or a vapor form is pumped through a coil of pipe which is immersed in a molten lead bath maintained at a temperature at which substantially no diphenyl is formed. This coil acts as a preheater, and serves to lessen the time of contact of the benzol with the higher temperature heating zone and thus avoids objectionable side reactions. When the benzol remains too long in a zone heated to that at which substantial quantities of diphenyl is formed excessive tar is formed along with the diphenyl. If the benzol is first introduced in a liquid form it is vaporized soon after it enters the pipe, and passes thereafter through the coil, during which passage it absorbs heat from the walls of the pi e and reaches the temperature of the bath y the 85 time it passes therefrom. The coil which is at the bottom of the bath isperforated, and the vapor streams out and in rising through the molten lead, in physical contact therewith, agitates the bath in such a'manner as to maintain a practically uniform temperature through the bath. By employing a large mass of lead, I am enabled to prevent overheating ofthevaporduetotheheatcapacityofthebath,

and by means of a thermocouple immersed therein, to observe temperature changes whichmay occur, and change the heating so as to supply additional heat or lessen the rate of heating, as may be desired. I prefer to operate the preheater bath at a temperastreams, out through holes in a distributor,

and then bubbles up through the lead in a manner similar to the preheater. The converter bath is kept at a temperature range of from 750 to 800 C. When the vapor passes from the converter bath it is passed, at

a high velocity, directly into a water-cooled condenser, so constructed that the vapor is quickly cooled and the unconverted benzene and the diphenyl are condensed and collected, While the hydrogen which is liberated when diphenyl is formed, is vented through a gasometer.

lln vaporizing the benzol and heating the vapors thereof there is an increase in volume amounting to substantially 800 times the original volume of the liquid ben'zol. The heated vapors are passed through conduits ofsuch cross sectional area that the velocity of the vapors is reatly. increased over the velocity of the liquld benzol fed to the heaters.

In operating my method according to the foregoing description, I am able to obtain "from 10% to 12% diphenyl formed per pass through the converter bath. If higher temperatures of the converter bath are employed,

a higher yield ,of diphenyl will be obtained; however,- the side reactions will form tarry bodies, and carbon will be formed, thereby uselessly consuming benzene.

- Apparatus in whichmy improved method is carried out is illustrated in the accompany- .ing drawings, forming a part of this application, wherein Fig. 1 is aplan view of the a paratus;

Fig. 2 is a sectional view ta en along the line IIII of Fig. 1; and

Fig. 3 is an enlarged plan view of the coil employed in the lower portion of the molten metal baths.

Referring to the drawings, I show a furnace 10 having separate heating chambers 11 and 12, divided by a wall 14 and each supplied with a fuel oil burner 13. In the chamber 11 is a vessel 16 and in the chamber, 12 is a vessel 17 each of the vessels being filled to the level shown in the drawing'with a substance 18, such as lead, which is molten at the temperatures employed: The chamber 11 is provided with a bafile wall 19 and the chamber 12- is provided with a bame wall 21 which walls diroot the heated productsof combustion around aeeaaee the vessels the combustion gases unite and pjass outwardly through a common flue 22;

ach of the vessels is supplied with a gastight cover 23. Extending downwardly mto the vessel 16 is-a coil of pipe 26 and extending downwardly into the vessel 17 is a pipe 27. Each of the pipes 26 and 27 terminates in a bottom 'coil 28, such as is shown in detail in' Fig. 3, and having a plurality of openings downwardly into the vessel 17 and which connects with a header 35 having connected thereto a plurality of conduits 37 each provided with a water jacket 38 having inlet and outlet connections 41 and 39 for quickly coolin g the heated vapor after it passes from the vessel 17.. lhe other ends of the conduits 37 are connected to a header 40. After passing through the 'water cooled condensing conduits 37, the condensate flows through a U: tube 46, connected to the header 40, and through a conduit 47 to a receiving tank 48. Connected to the header 40 is a vent 45' for hydrogen and other uncondensed gases. The U-tube 46is provided with a sight glass, 49 for observing the condensate. The storage tank 48 is provided with a breather vent opening 51 to permit ready filling and emptying thereof. In order that the temperatures within the vessels 16 and 17 may be observed and the supply of fuel regulated to give the desired por and the molten metal in the vessel. 1

also provide auges 58 to indicate the pressures of the henzol being pumped into the vessels and the outlet as it leaves the vessels.

Benzol is supplied to the apparatus from a suitable source of supply through a conduit 61 connected to a pump 62 and is discharged 26. fter being heated and condensed and collected in the storage tank 48, the-condensate is drained oil through a conduit 64 for fractional distillation in a well known manner.

In order that there shallbe no danger of explosions at starting, I provide a conduit 66, connected to the conduit 63 for forcing pressures of the vapor through a conduit 63 connected to the coil an inert gas, such as carbon dioxide, through the pipe and vessels before the benzol pump 62 isstarted. The conduit 66 is provided with suitable, valves 67 and 68 for controlling t-he supply of inert gas while the conduit 63 is provided with a valve 69 which is to be closed when the inert gas is being forced through the system.

From the foregoing description the operation of my improved apparatus will be apparent. Benzol is forced by the pump 62 through the conduit 63 into the coil 26 from which it bubbles upwardly through the molten metal in the vessel 16, which molten metal is maintained at a temperature range'of from 600 to 650 C., for preheating the benzol vapor. The preheated vapor passes quickly through the conduits 32 and 33 into the pipe 27 leading to the coil 28 in the bottom of the vessel 17, where the temperature range is from 750 to 800 C1, the temperature at which diphenyl is formed. The pipe 27 is made straight, except for the coil 28, in order that the vapor shall be in contact with the higher temperature bath only a suflicienttime to raise it to the required temperature. After bubbling upwardly through the molten metal in the vessel 17 the vapor is immediately" conveyed to the water cooled conduits 37 whereit is condensed and flows to the storage tank 48. 1 y

While there is an enormous increase in the volume of the benzol as its temperature is raised, the conduits through which the vapor is conveyed are not correspondingly increased in cross sectional area, so that the velocity of the vapor is progressively increased as it passes through the apparatus. This'is extremely important'in that it prevents reversal of the process andalso prevents objectionable side reactions while the I vapor is in the heated zone.

From the foregoing, it will be apparent that I have devised an improved method and apparatus for the production of diphenyl which is operable upon a commercial scale and wherein the temperature, rate of flow of vapor, and cooling of the vapor are under such control that a higher yield than has heretofore been possible is readily obtained.

While I have shown my invention, in but one form, it will-be obvious to those skilled in the art that it is not so limited but is susceptible of various changes and modifications without departing from the spirit thereof and I desire therefore that only such limitations shall be placed thereupon as are imposed by the prior art, or as are specifically set forth inthe appended claims' What claim is 1. lhe process. of producing diphenyl which consists in passing benzol vapors through a bath of a molten substance inert with respect to the vapors and heated to a temperature at WhlCh substantial quantities of diphenyl are formed, and condensing the vapors. v

2. The process of producing diphenyl which comprises passing benzol va'pors through a bath of a molten substance inert with respect to the vapors and heated to the maximum temperature at which substantial- I ly no diphenyl is formed, and immediately thereafter passing thev vapors thus heated through a similar bath heated to the tempera-- ture at whichsubstantial quantities of diphenyl are formed.

3. The process of producing diphenyl which comprises passing benzol vapors.

through a bath of a molten substance inert with respect to the vapors and heated to the maximum temperature at which substantially no diphenyl is formed, immediately thereafter passing the vapors thus heated through a similar bath heated to the temperature at which substantial quantities of diphenyl are formed, and immediately threafter cooling the vapors thus heated to condense them.

4. The process of producing diphenyl which comprises passing benzol vaporsbaths heated respective y to from 600 to 650 (1, and 750 to 800 C. x

6. The process for producing diphenyl which comprises passing benzol vapors progressively through apair of molten metal baths heated respectively to from 600 to 650 C. and750 to 800 (1., and quickly cooling the vapors thus heated while ata high vg/ locity. V r

7. The process of obtaining diphenyl from benzol which comprises passing benzol vapors upwardly through a bath of molten metal heated to a temperature at which diphenyl is formed, and quickly cooling the heated vapors to prevent reversal;

- -8. The process of obtaining diphenyl from benzol which comprises vaporizing liquid -benzol by subjecting it to the heat of a molten metal bath heated to a temperature at which substantially nodiphenyl is formed, forcing said vapors upwardly through the molten metal in contact therewith to preheat said vapors, forcmg the vapors thus preheated to a temperature at which diphenyl is formed,

through a second molten metalbath heated at V aeeaaea and quickly cooling the vapors to condense the di henyl. H

9. T e process of obtaining diphenyl from benzol which comprises passing benzol vapors in heat transfer relation with'a fluid medium inert with respect to the benzol vapors and heated to a temperature at which substantially no diphenyl is formed, and immediately thereafter passing the vapors thus preheated in heat transfer relation with a second similar fluid medium heated to a temperature at which diphenyl is formed.

10. The process of obtaining diphenyl from benzol which comprises passing benzol vapors in heat transfer relation with a fluid medium inert with respect to the benzol vapors and heated to a temperature at which substantially no diphenyl is formed and immediately thereafter passing the vapors thus preheated in heat transfer relation with a second similar fluid medium heated to a temperature at which diphenyl is formed, and quickly cooling the vapors thus heated to condense the diphenyl and unreactecl benzol and 25 to prevent reversal of the process.

11. Process of making diphenyl which comprises contacting benzol vapor with an inertliquid mass maintained at a temperature suficient to decompose the benzol.

12. Process of making diphenyl which comprises passing benzol vapor through a body of inert liquid maintained at a temperature sufiicient to decompose the benzol.

13. Process of 'malnng diphenyl which comprises passing benzol vapor through a body of molten lead maintained at a tempera- ,ture suflicient to decompose the benzol.

, 14. Process of making diphenyl which comprises heating benzol vapor to a temperature below but approaching the decomposition temperature of the benzol and delivering the heated benzol vapor into contact with a body of inert liquid maintained at a temperature sufiicient to decom ose the benzol.

In testimony whereof I afiix my signature.

THOMAS Jisoorr. 

